Methods for the epoxidation of an olefin with hydrogen peroxide using a water soluble manganese complex as epoxidation catalyst are known from D. E. De Vos et al., Tetrahedron Letters 39 (1998) 3221-3224 and from U.S. Pat. No. 5,329,024. WO 2010/012361 teaches to carry out the epoxidation in a biphasic system comprising an organic phase and an aqueous phase. WO 2010/012361 also suggests to add hydrogen peroxide at a rate about equal to the reaction rate of the catalytic epoxidation to ensure optimal peroxide efficiency.
WO 2011/107188 discloses use of a loop reactor for epoxidation with this catalyst in a multiphasic reaction mixture comprising an organic phase and an aqueous phase.
WO 2014/056603 discloses epoxidation with this catalyst in the presence of alkaline earth metal ions and suggests providing the oxidant at a concentration of from 0.05 to 4% by weight. In the examples, epoxidation is carried out in batch in a stirred vessel with a variable hydrogen peroxide feed aiming at a concentration of 0.1% by weight.
U.S. Pat. No. 6,774,992 discloses measuring the concentration of hydrogen peroxide in the aqueous phase of a pulp bleaching effluent. Raman intensities are measured at different wavenumbers to additionally determine amounts of further species present in the aqueous phase.